Estimation of indoor and outdoor effective doses and lifetime cancer risk from gamma dose rates in and around Mandya district, Karnataka

Indoor and outdoor gamma-ray dose rates have been measured in and around Mandya district (12 deg. 20'' N and 77 deg. 20'' E). The measurements were carried out from 45 locations of Mandya district at 1 m above the ground surface for radiometric, geophysical and environmental surveys using a lightweight portable radiation dosemeter ER-709. The indoor and outdoor absorbed gamma dose rate in air varied from 66.12±0.8 to 131.89±5.5 nGy per h with a geometrical mean value of 97.79±2.6 nGy per h and 45.94±0.7 to 80.39±2.6 nGy per h with a geometrical mean value of 58.75±1.5. The indoor and outdoor effective doses vary from 0.32 to 0.65 mSv per y with a geometric mean value of 0.48 mSv per y and 0.06 to 0.10 mSv per y with a geometric mean value of 0.07 mSv per y which is slightly higher when compared with the worldwide average of the effective doses. The indoor and outdoor excess lifetime cancer risk (ELCR) of residents along the different locations varies from 1.14 x 10^-3 to 2.26 x 10^-3 with a geometric mean value of 1.68 x 10^-3 and 0.20 x 10^-3 to 0.35 x 10^-3 with a geometric mean value of 0.25 x 10^-3 which is similar to the worldwide average of the ELCR. (authors)